The invention relates generally to support surfaces that facilitate blood flow and prevent tissue breakdown and more particularly to a molded foam cushion having suspension elements, particularly under the ischial area, that are shaped and positioned to form a shape matching support surface that has relatively uniform restoring forces when deformed under loads from of a user.
Individuals confined to sitting, for example in a wheelchair run the risk of tissue breakdown and the development of ischemic induced sores, which are extremely dangerous and difficult to treat and cure. For example, when seated much of the individual's weight concentrates in the region of the ischia, that is, at the bony prominence of the buttocks, and unless frequent movement occurs, the flow of blood to the skin tissue in these regions decreases to the point that the tissue breaks down. When lying down, the hip region may protrude deeper into the mattress than the adjoining waist or thigh regions and as a consequence the supporting forces exerted by the mattress would be greater at the hips than at the thighs or waist, for example. Any skin area where there are sustained deformation experiences reduced blood flow and the skin does not receive sufficient oxygen and nutrients.
It is desirable to have a support cushion applies generally uniform supporting forces, that is, a generally uniform counter force on the tissue of the ischial area of user positioned on the cushion. When a cushioning structure is deformed while supporting a person it is desirable to have a constant restoring force that exerts equal forces over a broader area of the body minimizing deformation of the soft tissues and help prevent skin and tissue breakdown by facilitating blood flow in the contacted area.